A very crude comparator, to be used with extreme caution, but nevertheless it's what you would expect: a gradual rise from 1500-1800 with some variation along the way. There is a marked difference between this more-or-less steady upward curve and that for OED quotations.

Note: The English Short Title Catalogue provides 'extensive descriptions and holdings information for letterpress materials printed in Great Britain or any of its dependencies in any language – as well as for materials printed in English anywhere else in the world. Coverage is from the beginnings of print to 1800 including all recorded English monographs printed between 1475 and 1700.'

The graph tells us therefore about the expansion of printing in English. Would we expect this to correlate with lexical expansion (increase in numbers of words and usages), and with increasing levels of literacy?